We are examining the details of structural polymorphism of the M,N glycoproteins of human erythrocyte membrane (glycophorin). Our approach is to compare glycoproteins isolated from individual donors of the M,N or MN blood types as well as immunologic and genetic variants of these blood groups. Our studies include comparison of the amino acid and carbohydrates structure of CNBr peptide A; in the coming year we plan to continue such studies. At present we are investigating the detailed studies of the complex N-asn linked oligosaccharide of the MN glycoproteins from individual donors. We plan to establish whether this unit is unique within the glycoprotein and fully processed and whether it is unique among individual donors. In the coming year we will initiate the amino acid sequence determination of the carboxy terminal CNBr peptide C isolated from M,N glycoproteins of individual donors.